Why do lower temperatures result in lower specific heat capacity?

In summary, the experiment involved placing a 100g mass in two beakers of water at different temperatures and recording the temperature changes. The specific heat capacity of the mass was then calculated using the equation E=mass of water x 4200*(T2-T1). This value was found to be lower at lower temperatures. The discussion also touched on the possibility of heat loss during the transfer of the mass between the beakers and the influence of factors such as the table and internal energy of the mass. It was suggested to do additional tests with faster transfer times to determine the effect of heat loss.
  • #1
Reety
4
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Member advised to use the homework template for posts in the homework sections of PF.
Equations: E=m*c* dTheta or T

Experiment: I had two beakers of water with one thermometer in each beaker. One beaker had boiling water and the other beaker had room temperature water. I also had a 100g mass.

I recorded T1 which was the intial temperature of the cold water.
I then put the mass of 100g into the boiling hot water and waited 30 seconds. I recorded this temperature as Tm which I assumed was the temperature of the 100g mass.

I then put the hot 100g mass into the cold water and recorded the maximum temperature rise and called this T2

I then worked out that E=mass of water x 4200*T2-T1
I then assumed that E of water = E of the mass
So then worked out that E=0.1kg*C*Tm-T2 and found a value for C

I then repeated this experiment for lower temperatures of Tm and therefore T2 and found a value for C... I found out that the lower temperatures of T got a lower specific heat capacity.. and the question is why?

My take on it so far is that when I lift the 100g mass out of the boiling water and put it into the cold beaker it transfers heat energy to the surroundings and the higher the temperature of Tm the more heat energy it transfers. Is this correct?

Thanks,
Reety.
 
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  • #2
Specific heat capacity is actually temperature dependent, that's why in physics books you see a different value than chemistry books.in chemistry books they measure it at 25 C and in physics they average it from 0-100. Your explanation of heat energy being lost while moving through the air is reasonable. If you wanted you could calculate that energy loss.there are several factors you will need though, emmisivity of material, and I there are values for the convection loss and conduction loss but I forget what they're called.
 
  • #3
I doubt that the mass lost a significant amount of heat in moving from one beaker to the other. How long did it take?

In the cold beaker, when you put the mass in and let the system equilibrate, you also changed the temperature of the beaker. Also, the table under the beaker? Did you take all that into account?
 
  • #4
462chevelle said:
Specific heat capacity is actually temperature dependent, that's why in physics books you see a different value than chemistry books.in chemistry books they measure it at 25 C and in physics they average it from 0-100. Your explanation of heat energy being lost while moving through the air is reasonable. If you wanted you could calculate that energy loss.there are several factors you will need though, emmisivity of material, and I there are values for the convection loss and conduction loss but I forget what they're called.

Ok thank you.

Chestermiller said:
I doubt that the mass lost a significant amount of heat in moving from one beaker to the other. How long did it take?

In the cold beaker, when you put the mass in and let the system equilibrate, you also changed the temperature of the beaker. Also, the table under the beaker? Did you take all that into account?

The transition between hot and cold beakers was only about 5-10 seconds. Aaah I didn't take into the account, yes maybe it lost some heat energy due to the transfer of energy to the table. But my teacher hinted it was something to due with the transition between taking the mass out of the hot beaker and placing it into the cold beaker.
 
  • #5
Also just a quick suggestion, do you think it could be due to the internal energy of the mass?
 
  • #6
Reety said:
Ok thank you.
The transition between hot and cold beakers was only about 5-10 seconds. Aaah I didn't take into the account, yes maybe it lost some heat energy due to the transfer of energy to the table. But my teacher hinted it was something to due with the transition between taking the mass out of the hot beaker and placing it into the cold beaker.
With all due respect to your teacher, I doubt that. The beaker is going to have to heat up too, and that will be significant. And the table is a significant heat sink also. You should at least calculate the amount of heat that goes into the beaker. Maybe the heat loss to the table would be about the same as that. Put some sort of insulation under the beaker so it doesn't contact the table directly, or, better yet, have the beaker raised in the air by some sort of metal ring frame.

If you want to test the heat-loss-in-the-transfer hypothesis, just do some additional tests where you do the transfer faster.
 
  • #7
Reety said:
Also just a quick suggestion, do you think it could be due to the internal energy of the mass?
The internal energy of the mass is the same as the heat capacity times the temperature, which is the thing you are measuring.
 
  • #8
Chestermiller said:
With all due respect to your teacher, I doubt that. The beaker is going to have to heat up too, and that will be significant. And the table is a significant heat sink also. You should at least calculate the amount of heat that goes into the beaker. Maybe the heat loss to the table would be about the same as that. Put some sort of insulation under the beaker so it doesn't contact the table directly, or, better yet, have the beaker raised in the air by some sort of metal ring frame.

If you want to test the heat-loss-in-the-transfer hypothesis, just do some additional tests where you do the transfer faster.

Yeah this makes so much more sense, thank you so much chestermiller.
 

Related to Why do lower temperatures result in lower specific heat capacity?

What is specific heat capacity?

Specific heat capacity is the amount of heat energy required to raise the temperature of one unit of mass of a substance by one degree Celsius or Kelvin.

How is specific heat capacity measured?

Specific heat capacity is typically measured using a calorimeter, which is a device that can measure the amount of heat energy absorbed or released by a substance during a temperature change.

Why is specific heat capacity important?

Specific heat capacity is important because it helps us understand how different substances behave when heated or cooled. It can also be used to calculate the amount of heat energy needed to change the temperature of a substance, which is useful in various industrial and scientific processes.

What factors affect the specific heat capacity of a substance?

The specific heat capacity of a substance can be affected by its molecular structure, density, and temperature. Substances with more complex molecular structures tend to have higher specific heat capacities, while substances with lower densities tend to have lower specific heat capacities.

How does specific heat capacity differ from heat capacity?

Specific heat capacity and heat capacity are often used interchangeably, but they are not exactly the same. Specific heat capacity is the amount of heat energy required to change the temperature of one unit of mass of a substance, while heat capacity is the amount of heat energy required to change the temperature of an entire object or system.

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